Methyl ketones acetophenones

If, on the other hand, unsymmetrically substituted carbonyl compounds such as monosubstituted benzophenones (X = OCH3, CH3, Cl), tert-butyl methyl ketone, acetophenone, acetaldehyde, or benzaldehyde are used for trapping 39a, diastere-omeric mixtures are formed in each case they could all be resolved except for the products obtained with p-methoxybenzophenone and acetophenone 33>. An X-ray structure analysis has been performed for the E-isomer 57g 36) which, in conjunction with H-NMR studies, permitted structural assignment in cases 56 and 57e, g and h35>. Additional chemical evidence for the structure of the six-membered heterocycles is provided by the thermolysis of 56 a considered in another context (see Sect. 3.1). In general the reaction 39a- 56 or 57 is accompanied by formation of phosphene dimers, presumably via [4 + 4]- and via [4 + 2]-cycloaddition 35). 

Compound (B), being an oxidation product of a ketone should be a carboxylic acid. The molecular formula of (B) Indicates that it should be benzoic acid and compound (A) should, therefore, be a monosubstituted aromatic methyl ketone. The molecular formula of (A) indicates that it should be phenyl methyl ketone (acetophenone). Reactions are as follows ... 

Structure and is defined by not only electron bnt also steric factors. With branching of the radical at the oxime function, the content of 4-methyl-snbstitnted pyrrole in the mixtnre increases. It is clearly seen if to compare the resnlts obtained for acetoxime, methyl isopropyl ketoxime and pinacoline oxime. Bulkier oximate anion, likely dne to the steric reasons, preferably attacks the C atom of methylacetylene. At the same time, cyclohexanone and 2-acetylfuran oximes react with the propyne in a regiose-lective manner to afford 5-methylpyrrole only. With oximes of ethyl methyl ketone, acetophenone, and 2-acetylthiophene, the yields of 5-methyl-snbstitnted pyrroles range 90%-92%. 

The student should note that ketones in class (1), t.c., those having the >CO group in the side chain, will form additive compounds with sodium bisulphite only if this >CO group is not directly joined to the benzene ring acetophenone therefore will not form such compounds, whereas benzyl methyl ketone, CaHsCHjCOCH, will do so. Many quinones, particularly ortho quinones such as phenanthraquinone, form additive compounds with sodium bisulphite. 

Ketones. Acetone, ethyl methyl ketone, diethyl ketone, acetophenone,... 

Acetone ethyl methyl ketone diethyl ketone acetophenone, ben-zophenone (and their nuclear-substituted derivatives). Cyclohexanone. 

Physical properties. Above members all colourless. Acetone, CH3COCH3, b.p. 56 soluble in water, characteristic odour. Ethyl methyl ketone, b.p. 80°, and diethyl ketone, b.p. 102 , are moderately and sparingly soluble in water respectively. Acetophenone,C6H5COCH3, m.p. 20, sparingly soluble, and benzophenone, m.p.48 ,... 

Acetic anhydride can be used to synthesize methyl ketones in Friedel-Crafts reactions. For example, benzene [71-43-2] can be acetylated to furnish acetophenone [98-86-2]. Ketones can be converted to their enol acetates and aldehydes to their alkyUdene diacetates. Acetaldehyde reacts with acetic anhydride to yield ethyhdene diacetate [542-10-9] (18) ... 

The type of synthesis in which the two-atom fragment supplies C-5 + C-6 is uncommon but useful in preparing pyrimidine- and 5,6,7,8-tetrahydroquinazoline-2,4-diamines. Thus, dicyandiamide (S78) with benzyl methyl ketone (S77) yields 6-methyl-5-phenylpyrimidine-2,4-diamine (S79), or with acetophenone it yields 6-phenylpyrimidine-2,4-diamine (62JOC2708). Likewise, with cyclohexanone it yields the tetrahydroquinazolinediamine (SSO) and by using N- substituted dicyandiamides, 2- and/or 4-alkylamino groups may be introduced (65JOC1837). 

The course of the reaction may involve either the acylation of the ketone to a -diketonic intermediate following thereupon the pathway in Section II, C, 2, a, or alternatively the condensation of two moles of ketone to yield an intermediate dypnone which then undergoes acylation following the pathway in Section II,C, l,a. Dilthey and Fischer thought the first alternative more plausible, on the basis of reaction yields, and this lead them to explore the pathway in Section II,C,2,a. Schneider and Ross and Diels and Alder believed that the second alternative operates. Both views are plausible since acylations of methyl ketones to S-diketones are known to take place in the conditions of this reaction, and dypnone ha.s been isolated from acetophenone on treatment with Friedel-Crafts catalysts, in the absence of an acid anhydride or chloride (an excess of catalyst... 

The Willgerodt reaction starts with the formation of an enamine 4 from the ketone, e.g. from acetophenone 3. The further course of the reaction cannot be described by a single mechanism that would apply to all examples known. For aryl methyl ketones 3 the mechanism for the Kindler variant is formulated as follows ... 

Outline methods for the preparation of acetophenone (phenyl methyl ketone) starting from the following ... 

Substituted acetophenones and a benzofuran were also isolated. The acetophenones may arise in a manner similar to that noted for 2,3-dihy-droxyphenyl methyl ketone (2,3-dihydroxyacetophenone) obtained from D-glucuronic acid. ... 

Scheme 6.3 Reaction scheme for the hydrogenation of acetophenone. AP acetophenone PE 1-phenylethanol CHMK cyclohexyl methyl ketone CHE 1-cyclohexylethanol ST styrene EB ethylbenzene and ECH ethylcyclohexane.

Table 6.13 Racemic hydrogenation of acetophenone" initial reaction rate rf, selectivity to products at 100% conversion. Results for the chemical reduction with NaBH4 are included for comparison. PE 1-phenylethanol, CHMK cyclohexyl methyl ketone and CHE 1-cyclohexylethanol. (Reproduced from Reference [34])...

The aromatic ketones that occur or are used as fragrance and flavor materials are predominantly aryl methyl ketones, which include acetophenones and /3-naphthyl methyl ketone. Several acetylpolymethylindanes and -tetralins are commercially important as musk fragrances. 

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